136 THE LIFE OF A BIRD. 



size of the bird. Dr. Jenner gave a minute 

 but philosophical attention to the subject of the 

 cuckoo's history ; and he found, on weighing 

 the largest cuckoo's egg he could obtain, that 

 it weighed only fifty-five grains. The smallest 

 weighed but forty-three grains. Of four speci- 

 mens in Mr. Yarrell's collection, the largest only 

 measures eleven lines and a half in length, and 

 eight lines and a half in breadth. " This," ob- 

 serves Mr. Yarrell, " is the exact size of the egg 

 of the skylark, yet the comparative size of the two 

 birds is as four to one." 



The invader generally deposits her egg during 

 the period when the small birds whose nests she 

 selects are occupied in the deposition of their 

 eggs. In the case of the hedge-warbler, and of 

 several other of these unfortunate birds which it 

 thus distinguishes, the time occupied for the depo- 

 sition of their eggs is about four or five days. 

 During this time the cuckoo, who has probably 

 been on the alert for a favourable opportunity, 

 taking advantage of the temporary absence of one 

 of the birds, slips her egg in, and hies away, 

 leaving her cares behind her, and the object of them 

 to the chanties of a pair of strangers. This in- 



